Added "Connecting to Maincloud" section to part-4.md (#275)

* Update part-4.md

added a proper main cloud section

* Update part-4.md

* Update docs/unity/part-4.md

* Apply suggestions from code review

---------

Co-authored-by: Tyler Cloutier <[email protected]>

Author: otdavies

docs/unity/part-4.md

@@ -578,6 +578,30 @@ We didn't even have to update the client, because our client's `OnDelete` callba
 
 Notice that the food automatically respawns as you vaccuum them up. This is because our scheduled reducer is automatically replacing the food 2 times per second, to ensure that there is always 600 food on the map.
 
+## Connecting to Maincloud
+- Publish to Maincloud `spacetime publish -s maincloud <your module name> --delete-data`
+  - `<your module name>` This name should be unique and cannot contain any special characters other than internal hyphens (`-`).
+- Update the URL in the Unity project to: `https://maincloud.spacetimedb.com`
+- Update the module name in the Unity project to `<your module name>`.
+- Clear the PlayerPrefs in Start() within `GameManager.cs`
+- Your `GameManager.cs` should look something like this:
+```csharp
+const string SERVER_URL = "https://maincloud.spacetimedb.com";
+const string MODULE_NAME = "<your module name>";
+
+...
+
+private void Start()
+{
+    // Clear cached connection data to ensure proper connection
+    PlayerPrefs.DeleteAll();
+    
+    // Continue with initialization
+}
+```
+
+To delete your Maincloud module, you can run: `spacetime delete -s maincloud <your module name>`
+
 # Conclusion
 
 :::server-rust